Method for preparing fluorinated compounds

Abstract

The invention relates to a method for selective dehydrofluorination on a mixed catalyst based on chromium and nickel on a carrier based on aluminium. The invention is used for the synthesis of 2,3,3,3-tetrafluoro-1-propene and 1,2,3,3,3-pentafluoro-1-propene.

1 . Selective dehydrofluorination process on a mixed catalyst based on chromium and nickel on a support based on aluminium. 
     
     
         2 . Dehydrofluorination process according to  claim 1  of a compound of formula (I) CF 3 —CHP—CHFX, in which X is hydrogen or fluorine to a compound of formula (II) CF 3 —CF═CHX, on a mixed catalyst based on chromium and nickel on a support based on aluminium. 
     
     
         3 . Process according to  claim 2 , in which the compound of formula (I) is the compound of formula (Ia) CF 3 —CHF—CHF 2  and the compound of formula (II) is the compound of formula (IIa) CF 3 —CF═CHF. 
     
     
         4 . Process according to  claim 3 , in which the compound of formula (I) is the compound of formula (Ib) CF 3 —CHF—CH 2 F and the compound of formula (II) is the compound of formula (IIb) CF 3 —CF═CH 2 . 
     
     
         5 . Process according to  claim 1 , in which the mixed catalyst comprises a chromium oxide, halide or oxyhalide in a mixture with a nickel oxide, halide or oxyhalide. 
     
     
         6 . Process according to  claim 1 , in which the mixed catalyst comprises a chromium fluoride or oxyfluoride in a mixture with a nickel fluoride or oxyfluoride. 
     
     
         7 . Process according to  claim 1 , in which the support based on aluminium is an aluminium halide or oxyhalide. 
     
     
         8 . Process according to  claim 1 , in which the support based on aluminium is an aluminium fluoride or oxyfluoride. 
     
     
         9 . Process according to  claim 1 , in which the catalyst comprises by weight 0.5 a 20% chromium and 0.5 to 20% nickel, these elements being present according to a molar ratio between 0.5 and 5. 
     
     
         10 . Process according to  claim 1 , implemented in gas phase. 
     
     
         11 . Process according to  claim 1 , implemented at a temperature comprised between 150° C. and 600° C., preferably between 300 and 500° C. and advantageously between 300 and 400° C. 
     
     
         12 . Process according to  claim 1 , implemented with a contact time comprised between 0.1 and 100 seconds, preferably between 1 and 50 seconds and advantageously between 2 and 20 seconds. 
     
     
         13 . Process according to  claim 1 , implemented in the presence of hydrogen, the molar ratio H 2 /1,1,1,2,3-pentafluoropropane being comprised between 0.3 and 30, in particular between 0.5 and 20, advantageously between 1 and 10. 
     
     
         14 . A method of performing a selective dehydrofluorination reaction comprising conducting dehydrofluorination in the presence of a mixed catalyst based on chromium and nickel on a support based on aluminium.